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I have a simple Windows Form with textbox. When form is loading, I start another class with counter. How to write to Form1.textBox1 from another class?
namespace Test_CSharp
{
public partial class Form1 : Form
{
public static Form1 form1;
public Form1()
{
InitializeComponent();
form1 = this;
}
private void Form1_Load(object sender, EventArgs e)
{
Run_Nonameclass();
}
private void Run_Nonameclass()
{
Nonameclass newNonameclass = new Nonameclass();
}
}
}
namespace Test_CSharp
{
class Nonameclass
{
private System.Timers.Timer mycounter;
public int cnt;
Form1 frm = new Form1();
public Nonameclass()
{
cnt = 0;
mycounter = new System.Timers.Timer();
mycounter.Interval = 1000;
mycounter.Start();
mycounter.Elapsed += mycounter_Tick;
}
private void mycounter_Tick(object source, System.Timers.ElapsedEventArgs e)
{
try
{
cnt = cnt + 1;
frm.textBox1.Text = cnt.ToString();
}
catch (Exception ex)
{
}
}
}
}
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You can't.
The Tick event happens asynchronously, but occurs on the same thread as the original code - so if your code starts a timer and then does a long running operation while loading you still won't see anything. The only way to get round that is to move the long running operation to a second thread (see the BackgroundWorker class[^] and report progress to the main thread to update the display.
And your code won't work, because your Nonameclass creates a new instance of the Form1 class which is never displayed. To display anything you would need to access the actual instance that created the Nonameclass instance and that means passing the Form1 instance to the constructor. Which is a bad idea, because it breaks OOPs and locks the two class designs together, as does exposing the TextBox publicly in your Form1 class!
You need to think about exactly what you are trying to achieve here, because the route you are trying to go is a bad idea. What you really want to do is probably possible, and even quite easy - but this way is not a good route to that (or anything else!)
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Hi, Folks.
I have a problem and expect you can help me. I use C# in Visual Studio 2019. I have a combobox which I populated with a table data. I used a Datasource to do this. When the user selects a value I need a variable to receive the string value of the combobox.
My snippet is as folows:
private void Cb_Campo_SelectionChangeCommitted(object sender, EventArgs e)
{
if (_Modo != 0)
{
Cb_Campo.DisplayMember = CampoTexto;
Cb_Campo.ValueMember = CampoChave;
ValorChave = int.Parse(Cb_Campo.SelectedValue.ToString());
ValorTexto = Cb_Campo.SelectedItem.ToString();
}
}
Before selection, the combobox has "Select" as a text. Tha variable ValorChave is receiving the correct value, but the variable ValorTexto, with the code above, receives "System.Data.DataRowView".
If I change that line for
ValorTexto = Cb_Campo.Text
The result is "Select", which is the initial text.
Obviously, what I need is the corresponding value to the SelectedValue.
Can anyone help me solve this?
Thanks a lot.
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The SelectedItem is a DataRow - as you'd expect because the ComboBox is bound to a DataSource.
And because DataRow is a "generic" class (in that it handle multiple types of data simultaneously) it doesn't handle ToString itself as it has no idea which bit(s) of data you might want it to convert to a string.
Try the Text property instead.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Hi, OriginalGriff.
As you can see in the main text, I've tried this, but is appears the combobox has't yet considered the selection the user did. Do you have any other sugestion?
Thanks.
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Are you using Autocomplete ? Did you try:
tryValorTexto = Cb_Campo.SelectedValue.ToString(); ?
«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali
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I use FFMediaToolkit package to do some video task like extract frame and remake video from frame image. My code sometime raise exception like below. I try to add try-catch block to handle it but no luck. Pls show me how to handle exception from ffmpeg lib.
Exception info:
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at FFMediaToolkit.Decoding.Internal.InputContainer.ReadPacket() in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\InputContainer.cs:line 174
at FFMediaToolkit.Decoding.Internal.InputContainer.GetPacketFromStream(Int32 streamIndex) in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\InputContainer.cs:line 90
at FFMediaToolkit.Decoding.Internal.Decoder.DecodePacket() in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\Decoder.cs:line 146
at FFMediaToolkit.Decoding.Internal.Decoder.ReadNextFrame() in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\Decoder.cs:line 136
at FFMediaToolkit.Decoding.VideoStream.GetNextFrame() in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\VideoStream.cs:line 51
at FFMediaToolkit.Decoding.VideoStream.TryGetNextFrame(ImageData& bitmap) in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\VideoStream.cs:line 68
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We can't help you at all based on that: your code is calling an external DLL and passing bad data, eitehr in the form of a bad media, or a bad address for data.
And since we can't see your code at all, we have no idea what functions you are calling, how you are calling them, or what data you might be passing.
Sorry, but you will have to sort this out yourself!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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[HandleProcessCorruptedStateExceptions]
[SecurityCritical]
private void timerCallback(object state)
{
MediaFile file = null;
long startTick = DateTime.Now.Ticks;
try
{
if (PlayListInfo == null || PlayListInfo.Count == 0) return;
int idx = 0;
bool newVideo = true;
TimeSpan endTime = new TimeSpan();
double time_4_frame_ms = 0;
while (idx < PlayListInfo.Count && !request_stop)
{
var startProcess = DateTime.Now;
var curVideo = PlayListInfo[idx];
bool firstFrame = false;
if (newVideo)
{
if (file != null) file.Dispose();
startTick = DateTime.Now.Ticks;
file = MediaFile.Open(curVideo.fileName);
newVideo = false;
endTime = curVideo.stopTime < 0 ? file.Info.Duration : TimeSpan.FromSeconds(curVideo.stopTime);
if (!file.HasVideo)
{
Console.WriteLine($"Cannot load video file: {curVideo.fileName}");
}
else
{
Console.WriteLine($"Process video: {curVideo.fileName}, frame rate: {file.Video.Info.AvgFrameRate}");
time_4_frame_ms = file.Video.Info.NumberOfFrames == null ? 0 : file.Video.Info.Duration.TotalMilliseconds / file.Video.Info.NumberOfFrames.Value;
firstFrame = true;
}
}
TimeSpan sp = new TimeSpan(DateTime.Now.Ticks - startTick);
sp.Add(TimeSpan.FromSeconds(curVideo.startTime <= file.Info.StartTime.TotalSeconds ? file.Info.StartTime.TotalSeconds : curVideo.startTime));
ImageData img;
if (sp > endTime)
{
idx++;
newVideo = true;
continue;
}
if (file != null && file.HasVideo)
{
var t1 = DateTime.Now;
bool ck = false;
if (firstFrame)
{
ck = file.Video.TryGetFrame(sp, out img);
firstFrame = false;
}
else
{
do
{
ck = file.Video.TryGetNextFrame(out img);
}
while (ck && file.Video.Position < sp);
}
if (!ck)
{
Console.WriteLine($"Cannot read frame at {sp} of {curVideo.fileName}");
idx++;
newVideo = true;
continue;
}
else
using (var bitmap = ToBitmap(img))
{
var frametime = DateTime.Now - t1;
if (checkBlankFrame(bitmap))
{
Console.WriteLine($"Found black frame at {sp} of {curVideo.fileName}");
}
else ProcessFrame(bitmap);
}
}
var processTime = DateTime.Now - startProcess;
int sleeptime = (int)(time_4_frame_ms - processTime.TotalMilliseconds);
if (sleeptime > 0)
System.Threading.Thread.Sleep(sleeptime);
}
}
catch (AccessViolationException ex)
{
Console.WriteLine(ex.ToString());
}
catch
{
}
finally
{
if (file != null)
{
try
{
file.Dispose();
}
catch
{
}
file = null;
}
}
}
here is the source code for making video from bitmap:
private unsafe void PushFrame(Bitmap bitmap)
{
try
{
lock (this)
{
var data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
try
{
int len = data.Stride * data.Height;
byte[] bitmapData = new byte[len];
Marshal.Copy(data.Scan0, bitmapData, 0, len);
if (frameList.Count == 0) startTime = DateTime.Now.Ticks;
frameList.Add(bitmapData);
}
finally
{
bitmap.UnlockBits(data);
}
TimeSpan sp = new TimeSpan(DateTime.Now.Ticks - startTime);
if (sp.TotalSeconds >= Properties.Settings.Default.LiveVideoDuration)
{
if (frameList.Count == 0) return;
videoCount++;
videoIndex = videoCount % 10;
var settings = new VideoEncoderSettings(width: bitmap.Width, height: bitmap.Height,
framerate: (int)(frameList.Count / sp.TotalSeconds), codec: VideoCodec.H264);
settings.EncoderPreset = EncoderPreset.Fast;
settings.CRF = 17;
string path = $"{VideoFolder}\\{videoIndex}.{videoExt}";
using (var mediaFile = MediaBuilder.CreateContainer(path).WithVideo(settings).Create())
{
Console.WriteLine($"create video: {MappingFile}.{videoIndex}.{videoExt} -- duration: {sp.TotalSeconds}, total frame: {frameList.Count}");
foreach (var item in frameList)
{
Span<byte> imgData = new Span<byte>(item, 0, item.Length);
mediaFile.Video.AddFrame(new ImageData(imgData, ImagePixelFormat.Bgr24, bitmap.Size));
}
AddFileToPlayList(videoCount, $"{videoIndex}.{videoExt}", (decimal)sp.TotalSeconds);
}
frameList.Clear();
}
}
}
catch(Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
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I am not going to sit here and wade through an entire, badly indented, unformatted, uncommented, large application that I can't even begin to test to try and work out where an error might be happening, and from that what might possibly be causing it.
Would you?
Use the debugger. Narrow down where it fails, and when it fails. Look at the variables you are passing to methods when it fails. Compare them against what you expected.
We can't do any of that for you!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Oh may be my english is not good enough so you still confuse about the code sample. You don't need to understanding what I doing in the code statement. Just look at that then you will see the try-catch block cover all code that I use ffmpeg lib to do. My question is: when exception from ffmpeg raised, why it let my application scrash instead of jump to catch statement.
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WOW! You did a really bad thing by what appears to be creating your entire application in a single method. That's some real spaghetti code and is probably the source of your problem. The first thing you need to fix is the indentation. It's impossible for you, or anyone else, to follow that code because you have no idea what lines below to which if or using statements.
You REALLY need to scrap this code and rethink it. Methods should do ONE thing and one thing only. Break your work flow down into smaller and smaller chunks until you get each chunk down to doing one thing. Then you can write code for methods to do those one things.
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Dave Kreskowiak wrote: Then you can write code for methods to do those one things.
And possibly even test them. 
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Oh may be my english is not good enough so you still confuse about the code sample. You don't need to understanding what I doing in the code statement. Just look at that then you will see the try-catch block cover all code that I use ffmpeg lib to do. My question is: when exception from ffmpeg raised, why it let my application scrash instead of jump to catch statement.
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Your English is fine, it is your code that is the problem. Look at these catch blocks:
catch (AccessViolationException ex)
{
Console.WriteLine(ex.ToString());
}
catch
{
}
So all of those exceptions are just ignored and your program continues on, until it tries to do something that causes it to crash.
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That is the problem. I write catch block to catch all exception raised from the main code but it cannot catch exception from FFMediaToolkit. My app is crashed and show below exception on debuger:
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at FFMediaToolkit.Decoding.Internal.InputContainer.ReadPacket() in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\InputContainer.cs:line 174
at FFMediaToolkit.Decoding.Internal.InputContainer.GetPacketFromStream(Int32 streamIndex) in C:\projects\ffmediatoolkit\FFMediaToolkit\Decoding\Internal\InputContainer.cs:line 90
at FFMediaToolkit.Decoding.Internal.Decoder.DecodePacket() in
....
Atfter that, I try to add block "catch (AccessViolationException ex)" but no luck. I'm thinking about something that I need to add to my code to catch native (or unmanage exception) but I don't have any idea about it.
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I just think about one more case: FFMediaToolkit call ffmpeg lib and it create a new thread to process may task (extract frame, encode video.. etc) and when exception occur, my app canot catch the exeption in my way because it raised from difference thread.
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As I already told you, you are ignoring the exceptions in your catch blocks, so you cannot expect your program to work without problems. You must handle the exception; at the very least display a message. Until you do that you cannot be certain what is happening in your code.
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Thanks for your guide. I summary something about my problem:
My code statement like below:
try
{
}
catch
{
}
My main code can raise exception at anytime depend on bad situation (bad code, bad input video file,..etc) and we don't care about why it raise the excption in main code block, and whatever reason, it must be jump to catch statement when exception raise. But it didn't jump in catch block, in fact. I'm sure about, because I've ever take break point, add debug print exception, and some otherway. So at this time, I'm thinking about the reason come from the way ffmpeg process video. It run on other thread so when exception is raised, it does not go to catch block.
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Since your catch block has no code you have no idea what happens, and no way to find out.
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Oh may be my english is not good enough so you still confuse about the code sample. You don't need to understanding what I doing in the code statement, I get some statements that use ffmpeg lib. Just look at that then you will see the try-catch block cover all code that I use ffmpeg lib to do. My question is: when exception from ffmpeg raised, why it let my application scrash instead of jump to catch statement.
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I understood the English.
You're not understanding the problem. It's not with the library or the system. It's your code.
You ARE catching the exceptions. The problem is you're not handling them correctly. Your error handling is so bad that you handle the exception in one place, and don't fix anything, letting the code continue on using bad data and causing another problem further down the line.
Your bigger problem is that nobody is going to go through that pile of garbage code to tell you "oh, just do this little thing and you'll be good". There is no fixing that code because it's so poorly written. This is a scrap it and rewrite fix.
You REALLY need to break your problem down into smaller and smaller parts so you can write methods that do one thing and one thing only.
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I'm not sure why this is giving me an issue, I am not very in depth in c#.
Uri webAddress = new Uri("http://" + textBox1.Text);
WebRequest request = WebRequest.Create(webAddress);
webrequest is having issue CS1929, "button does not contain a definition for 'create' and the best extension method overload 'FileSystemAcIExtensions.Create(DirectoryInfo, DirectorySecurity)' requires a receiver of type 'DirectoryInfo'"
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From those lines we can't be certain, but ... I'd say that the most likely reason is that you have a Button on your form called WebRequest, and it's being searched for the Create method, which a Button will not have.
If so, there are two ways to fix it:
1) Change the name of the Button.
2) Use a fully qualified name for WebRequest:
System.Net.WebRequest request = System.Net.WebRequest.Create(webAddress);
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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the button name was exactly the problem, thank you so much.
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